Method for providing a hermetically sealed capacitor

ABSTRACT

A sealed capacitor, which may be hermetic, having a generally flat, planar geometry, is described. The capacitor includes at least one electrode provided by a metallic substrate having a capacitive material contacted thereto. The coated substrate can provide at least one of the casing side walls itself or, be connected to the side wall. A most preferred form of the capacitor has the conductive substrate provided with the capacitive material formed from an ultrasonically generated aerosol.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of U.S.application Ser. No. 08/847,948, filed May 1, 1997, now U.S. Pat. No.5,926,362 to Muffoletto et al.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a capacitor, and moreparticularly, to a capacitor having a substantially flat, planargeometry. Still more particularly, the present invention relates to ametallic substrate provided with capacitive material contacted theretoand incorporated into a hermetically sealed casing to provide at leastone of the electrodes for the capacitor. The metallic substrate canprovide at least one of the casing side walls itself or be connected tothe side wall. A most preferred form of the capacitor has the conductivesubstrate provided with a pseudocapacitive material formed from anultrasonically generated aerosol.

2. Prior Art

Standard capacitor construction consists of a cylindrically shaped casehousing an anode electrode and a cathode electrode. For example,standard wet slug tantalum capacitors generally have a cylindricallyshaped conductive casing serving as the terminal for the cathodeelectrode with the tantalum anode connected to a terminal leadelectrically insulated from the casing by a glass-to-metal insulator andseal structure. The anode insulator and seal structure is disposedeither internally or externally of the casing. The opposite end of thecasing is also typically provided with an insulator structure. Thecylindrical shape limits the internal volume inside the capacitor andthe closing seal structures occupy volume that detracts from thecapacitor's volumetric efficiency.

Furthermore, the capacitor of the present invention having a flat,planar shape can comprise either an electrochemical type capacitor orelectrolytic type capacitor. The anode and/or the cathode in a typicalelectrochemical capacitor or the cathode in an electrolytic capacitorgenerally include a substrate of a conductive metal such as titanium ortantalum having a capacitive material provided thereon. In that respect,the capacitive material may be in the form of an anodized-etched foil, asintered active material with or without oxide, a double layercapacitive material such as a carbonaceous capacitive material orplatinum black, a semiconductive material, pseudocapacitive materialsuch as a redox or under potential material, and conducting polymers.Commonly used coating techniques for contacting these materials to thesubstrate include dipping, sputtering and pressurized air atomizationspraying of a solution of the capacitive material onto the substrate.Capacitance values for electrodes made by these prior art techniques arelower in specific capacitance than an electrode coated with anultrasonically generated aerosol of active material according to thepresent invention. Sol-gel deposition is another prior art method ofcoating a substrate, and this method also provides capacitor electrodeslower in specific capacitance than ultrasonically generated aerosolcoatings.

SUMMARY OF THE INVENTION

The present invention provides a hermetically sealed capacitor housed ina casing having a generally flat, planar profile. Additionally, thepresent capacitor having the flat, planar shape provided by spaced apartside walls joined by a surrounding intermediate wall includes an anodeelectrode and a cathode electrode, at least one of which is comprised ofa conductive substrate having capacitive properties itself or, acapacitive material contacted thereto. The active material may becontacted to the substrate in the form of an ultrasonically generatedaerosol of the active material. The conductive substrate is fabricatedto the desired shape of the casing side wall serving as one electrodeterminal with the active material in electrical association with acounter electrode or, the conductive substrate is electrically connectedto the casing.

These and other aspects of the present invention will become moreapparent to those skilled in the art by reference to the followingdescription and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan, cross-sectional view of a capacitor 10 according tothe present invention.

FIG. 2 is an elevational, cross-sectional view of the capacitor 10 shownin FIG. 1.

FIG. 3 is an elevational, cross-sectional view of the capacitor 10 shownin FIG. 2 rotated 90 degrees.

FIGS. 4 to 7 are fragmentary, cross-sectional views of alternateembodiments of insulator and seal structures for a terminal lead 34 forthe capacitor 10.

FIG. 8 is an elevational, cross-sectional view of an electrodelead-to-lead construction for a capacitor according to the presentinvention.

FIG. 9 is an elevational, cross-sectional view of an alternateembodiment of a lid 104 closing the capacitor casing.

FIGS. 10, 10A and 11 are fragmentary, cross-sectional views of variousembodiments of closure structures for the capacitor 10.

FIGS. 12 to 15 are elevational, cross-sectional views of variousalternate embodiments of capacitors according to the present invention.

FIG. 16 is an elevational, cross-sectional view of side-by-sidecapacitors 188 and 190 connected in parallel.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIGS. 1 to 3 illustrate an exemplarycapacitor 10 according to the present invention. Capacitor 10 comprisesan anode 12 and a cathode 14 housed inside of a hermetically sealedcasing 16. The capacitor electrodes are activated and operativelyassociated with each other by an electrolyte contained inside the casing16, as will be described in detail hereinafter. It should be pointed outthat the capacitor 10 can be of either an electrochemical type whereinboth the anode and the cathode electrodes are provided by conductivesubstrates having a capacitive material contacted thereto according tothe present invention or, of an electrolytic type wherein the cathodeelectrode is provided by a conductive substrate having capacitiveproperties. The exemplary capacitor 10 illustrated in FIGS. 1 to 3 is ofthe latter type, however, this should not be construed as limiting.

Casing 16 includes a deep drawn can 18 having a generally rectangularshape comprised of spaced apart side walls 20 and 22 extending to andmeeting with opposed end walls 24 and 26 extending from a bottom wall28. A lid 30 is secured to the side walls 20, 22 and the end walls 24,26 by a weld 32 to close the casing 16. Casing 16 is of a conductivemetal and as such serves as one terminal or contact for makingelectrical connection between the capacitor and its load. The weld isprovided by any conventional means, however, a preferred method is bylaser welding.

The other electrical terminal or contact for the capacitor 10 isprovided by a conductor or lead 34 extending from within the capacitor10 through casing 16 and in particular through lid 30. Lead 34 isinsulated electrically from the metal lid 30 by an insulator and sealstructure 36, which will be described in detail presently. Anelectrolyte fill opening 38 in lid 30 is closed by a closure structure40, in a manner which will be described in detail hereinafter.

The cathode electrode 14 is spaced from the anode electrode 12 housedinside the casing and comprises an electrode active material 42 providedon a conductive substrate. The active material has a thickness of abouta hundred Angstroms to about 0.1 millimeters. When the casing 16 servesas one terminal or contact for the capacitor, the casing, and inparticular the can 18, serves as the conductive substrate or, theconductive substrate provided with the active material 42 iselectrically connected to the can 18. In either case, the conductivesubstrate is selected from the group consisting of tantalum, titanium,nickel, molybdenum, niobium, cobalt, stainless steel, tungsten,platinum, palladium, gold, silver, copper, chromium, vanadium, aluminum,zirconium, hafnium, zinc and iron, and mixtures and alloys thereof. Thelid 30 is also preferably of one of the above conductive materials.Preferably the conductive substrate has a thickness of about 0.001 to 2millimeter.

Preferably the substrate is cleaned of contaminants by lubricants fromhandling equipment or body oils from hands and the like and roughened bychemical or mechanical means to increase its surface area prior to beingcontacted with the active material 42. If desired, the electricalconductivity of the uncoated substrate can be improved by a techniquedescribed in U.S. application Ser. No. 08/847,946 entitled “Method ofImproving Electrical Conductivity of Metals, Metal Alloys and MetalOxides”, which is assigned to the assignee of the present invention andthe disclosure of which is incorporated herein by reference.

After preparation, the active material 42 is contacted to the conductivesubstrate preferably after but possibly before the prepared substrate iscut, shaped or otherwise fabricated into the desired geometry. Toprovide a capacitor electrode, the substrate may be of ananodized-etched conductive material, have a sintered active materialwith or without oxide contacted thereto, be contacted with a doublelayer capacitive material, for example a finely divided carbonaceousmaterial such as graphite or carbon or platinum black, a semiconductivematerial, a redox, pseudocapacitance or an under potential material, oran electroactive conducting polymer such as polyaniline, polypyrole,polythiophene and polyacetylene, and mixtures thereof. As will bedescribed in detail hereinafter, the capacitive material is preferablycontacted to the conductive substrate in the form of an ultrasonicallygenerated aerosol of the conductive material. In the case of the can 18serving as the conductive substrate, an articulating spray head of awell known type is used to coat the interior surfaces of the can 18 withthe ultrasonically generated aerosol of the desired material. FIGS. 1 to3 show that the majority of side walls 20 and 22 are provided with theelectrode active material 42. Other configurations of active materialcontacted to the conductive side walls are contemplated by the scope ofthe present invention as needed for a particular capacitor application.

According to one preferred aspect of the present invention, the redoxactive material 42 includes an oxide of a first metal, the nitride ofthe first metal, the carbon nitride of the first metal, and/or thecarbide of the first metal, the oxide, nitride, carbon nitride andcarbide of the first metal having pseudocapacitive properties. The firstmetal is preferably selected from the group consisting of ruthenium,cobalt, manganese, molybdenum, tungsten, tantalum, iron, niobium,iridium, titanium, zirconium, hafnium, rhodium, vanadium, osmium,palladium, platinum, nickel and lead.

The redox active material 42 may also include a second or more metals.The second metal is in the form of an oxide, a nitride, a carbon nitrideor a carbide, and is not essential to the intended use of the conductivesubstrate as a capacitor electrode and the like. The second metal isdifferent than the first metal and is selected from one or more of thegroup consisting of tantalum, titanium, nickel, iridium, platinum,palladium, gold, silver, cobalt, molybdenum, ruthenium, manganese,tungsten, iron, zirconium, hafnium, rhodium, vanadium, osmium, andniobium. In a preferred embodiment of the invention, the active materialproduct 42 includes oxides of ruthenium or ruthenium and tantalum.

In accordance with one embodiment of the present invention, thefabricated can 18 is provided with the active material 42 containing atleast the first pseudocapacitive metal and possibly the second or moremetals deposited on the side walls 20 and 22 of can 18 (FIG. 3) servingas the conductive substrate. Alternatively and as will be described indetail hereinafter, a conductive substrate of one of the enumeratedmaterials is first provided with the redox active material coating andthe thusly processed substrate is then contacted to the casing sidewalls (FIGS. 12 to 16). As previously discussed, the processedconductive substrate can provide the anode and/or the cathode in anelectrochemical capacitor, or the cathode in an electrolytic capacitor.The exemplary capacitor shown in FIGS. 1 to 3 is of the electrolytictype and the cathode active material preferably coats the side wallsbeginning at a position spaced from the bottom wall of the casing to adistance spaced from the lid. Such a coating is accomplished byproviding the conductive substrate with a masking material in a knownmanner so that only an intended area of the substrate is contacted withactive material. The masking material is removed from the substrateprior to capacitor fabrication. Preferably, the cathode active materialis substantially aligned in a face-to-face relationship with the anodemajor surfaces.

A preferred coating process is described in U.S. Pat. No. 5,894,403 toShah et al., entitled “Ultrasonically Coated Substrate For Use In ACapacitor And Method Of Manufacture” or, by the coating processdescribed in U.S. Pat. No. 5,920,455 to Shah et al., entitled “One StepUltrasonically Coated Substrate For Use In A Capacitor”. Theseapplications are both assigned to the assignee of the present inventionand the disclosures thereof are incorporated herein by reference. Inthat manner, the ultrasonically generated active material contacted tothe conductive substrate has a majority of its particles with diametersof less than about 10 microns. This provides an internal surface areafor the active material of about 10 m²/gram to about 1,500 m²/gram.

The anode electrode 12 is typically of a metal selected from the groupconsisting of tantalum, aluminum, titanium, niobium, zirconium, hafnium,tungsten, molybdenum, vanadium, silicon and germanium, and mixturesthereof in the form of a pellet. As is well known by those skilled inthe art, the anode metal in powdered form, for example tantalum powder,is compressed into a pellet having an anode lead 34 extending therefrom,and sintered under a vacuum at high temperatures. The porous body isthen anodized in a suitable electrolyte to fill the pore with theelectrolyte and to form a continuous dielectric oxide film on thesintered body. The assembly is then reformed to a desired voltage, as iswell known by those skilled in the art to produce an oxide layer overthe terminal lead/anode lead weld. The anode can also be of an etchedaluminum or titanium foil or, a sintered aluminum or titanium body.

A separator structure of electrically insulative material is providedbetween the anode 12 and the cathode 14 to prevent an internalelectrical short circuit between the electrodes. The separator materialalso is chemically unreactive with the anode and cathode activematerials and both chemically unreactive with and insoluble in theelectrolyte. In addition, the separator material has a degree ofporosity sufficient to allow flow therethrough of the electrolyte duringthe electrochemical reaction of the capacitor 10. Illustrative separatormaterials include woven and non-woven fabrics of polyolefinic fibersincluding polypropylene and polyethylene or fluoropolymeric fibersincluding polyvinylidene fluoride, polyethylenetetrafluoroethylene, andpolyethylenechlorotrifluoroethylene laminated or superposed with apolyolefinic or fluoropolymeric microporous film, non-woven glass, glassfiber materials and ceramic materials. Suitable microporous filmsinclude a polyethylene membrane commercially available under thedesignation SOLUPOR (DMS Solutech), a polytetrafluoroethylene membranecommercially available under the designation ZITEX (Chemplast Inc.), apolypropylene membrane commercially available under the designationCELGARD (Celanese Plastic Company, Inc.) and a membrane commerciallyavailable under the designation DEXIGLAS (C. H. Dexter, Div., DexterCorp.). Cellulose based separators also typically used in capacitors arecontemplated by the scope of the present invention. Depending on theelectrolyte use, the separator can be treated to improve itswettability, as is well known by those skilled in the art.

FIGS. 1 to 3 illustrate one embodiment of a separator structureaccording to the present invention wherein spaced apart sheets of 44, 46of one of the above-referenced separator materials, for example sheetsof microporous, polyolefinic film, are connected to a polymeric ring 48.The sheets 44 and 46 are disposed intermediate the anode 12 and thecoated side walls 20 and 22, respectively, serving as the cathodeelectrode 14. The microporous structure provides for ion flowtherethrough during charge and discharge cycles while the polymeric ring48 frames the sheets 44, 46 to provide structural support for them.Alternatively, the polymeric ring can be eliminated and the separatorsheets 44, 46 are sealed to each other in a known manner at theirperipheries to envelope the anode 12.

As shown in enlarged detail in FIG. 4, the insulator and seal structure36 for the terminal lead 34 comprises a header or ferrule element 50defining an internal cylindrical through bore or passage 52 of constantinside diameter. An outwardly facing step 54 is provided at the upperend of ferrule 50 having an outer surface sized to fit in an opening 56(FIGS. 2 and 3) in lid 30 with the upper end of ferrule 50 securedtherein by welding and the like. The terminal lead 34 is secured andsealed within ferrule by a series of sealing materials. A first layer isprovided by a disc or plug 58 of synthetic polymeric material having anannular groove 60 that receives the lower end of the ferrule 50 seatedtherein. A second layer 62 is of synthetic polymeric material such aselastomeric materials that are capable of sealing between lead 34 andthe inner surface of ferrule 50 and which can be the same as ordifferent than the first layer. The second layer 62 is provided inferrule 50 contacting the plug 58 and a suitable material is, forexample Master-Sil 151 made by Master Bond. Finally, a glass layer 66provides a hermetic seal between the inside of the ferrule 50 and theterminal lead 34. The glass used is, for example Elan Type 88 or MansolType 88. The anode terminal lead 34 preferably comprises the samematerial as the anode 12.

FIG. 5 shows another embodiment of an insulator and seal structure 66for terminal lead 34 according to the present invention wherein acup-shaped synthetic polymeric member 68 receives the ferrule 50 restingon a base portion of the cup 68. A compression ring 70 is sized tosurround the annular wall of cup member 68 thereby biased in a sealingengagement with the outer surface of ferrule 50. A second, polymericlayer 72, a third, polymeric layer 74 and fourth, glass layer 76 arethen provided in the ferrule 50 sealing between bore 52 and lead 34 in asimilar manner as previously described with respect to the sealstructure 36 shown in FIG. 4.

FIG. 6 illustrates another embodiment of an insulator and seal structure78 for terminal lead 34 according to the present invention including afirst layer 80 of synthetic polymeric material, a second, syntheticpolymeric layer 82, a third, polymeric layer 84 and a fourth, glasslayer 86 provided successively in the ferrule 50 sealing between bore 52and lead 34 in a manner similar to the insulator and seal structuresshown in FIGS. 4 and 5.

FIG. 7 shows an alternate embodiment of an insulator and seal structure88 according to the present invention including a metal sleeve 90 fittedaround and along a portion of the terminal lead 34 inside the ferrule50. Sleeve 90 has an inner diameter that is somewhat greater than theouter diameter of lead 34. The first and second synthetic polymericlayers 92 and 94 and a portion of a third, polymeric layer 96 sealbetween lead 34 and the bore 52 of the ferrule 50. An upper portion ofthe third, polymeric layer 96 and a fourth, glass layer 98 seal betweenbore 52 and the outer surface of sleeve 90. A weld 100 between sleeve 90and lead 34 at their upper ends completes the hermetic structure.Insulator and seal structure 88 provides for economy of manufacture asit can be secured in ferrule by layers 96,98 before capacitor assembly.Then, the terminal lead 34 is moved through the sleeve 90, layers 92 and94 are filled into the ferrule and the terminal lead 34 is welded to thesleeve 90 at 100.

FIGS. 2 and 3 show the insulator and seal structure 36 of FIG. 4incorporated into the capacitor 10. The anode 12 is provided with anotch forming a step 102 adjacent to end wall 26 of can 18. Step 102provides clearance for the insulator and seal structure 36. In thatmanner, the portion of anode terminal lead 34 extending outside thecapacitor 10 for connection to the load is hermetically sealed from theinterior of the capacitor 10 and insulated from the can 18 and lid 30serving as the terminal for the cathode electrode 14.

It will be apparent to those skilled in the art that in addition toconstructing the capacitor having the various insulator and sealstructures disposed inside the casing with the upper end of ferrule 50slightly protruding or flush with the lid 30, the insulator and sealstructures can also be mounted on the lid 30. For example, in theinsulator and seal structure 66 shown in FIG. 5, the compression ring 70can be welded to the lid 30 surrounding the opening 54. In the case ofthe insulator and seal structures 78 and 88 shown in FIGS. 6 and 7,respectively, the lower end of ferrule 50 can be welded to the uppersurface of lid 30 such that the ferrule surrounds the opening 54.Furthermore, it should be understood that the various syntheticpolymeric materials need not necessarily be in the exact arrangementsshown. These materials can be provided in any order desired or, they maybe provided independently as required to protect the glass layer fromthe electrolyte and from voltage breakdown. Also, the encapsulate layersused in the terminal ferrule can be filled therein either before orafter the anode 12 and lead 34 are connected together and formed to adesired voltage.

FIG. 8 shows an alternate embodiment of the capacitor 10 according tothe present invention having a terminal lead 34A provided with aU-shaped portion 34B disposed inside the casing 18. The lead 34A isinsulated from the can 18 and lid 30 by the insulator and seal structure78 shown in FIG. 6. The anode 12 is provided with an anode conductor 101connected to U-shaped terminal lead portion 34B by a weld 103. Thislead-to-lead construction can be used in addition to the insulator andseal structures shown in FIGS. 4 to 7.

After the cathode electrode 14 is disposed inside the can 18, the anodeelectrode 12 and the lid 30 as an assembly are fitted to the upper endof the can 18 and welded in place to provide a hermetic seal between thecan and the lid. As shown in FIGS. 2 and 3, the lid 30 comprises a platemember having a shape sized to fit snugly inside the inner surface ofthe open end of can 18 and flush with the upper end thereof. The lid 30is then secured in place by weld 32. In an alternate embodiment shown inFIG. 9, a lid 104 has a first, larger body portion 106 and a second,smaller body portion 108 which meet at a step 110 which is sized to bereceived by the upper end of a can 112. In that position, thesurrounding wall of the first lid portion 106 is flush with the outerside wall of the can 112 and the surrounding wall of the second lidportion is in a snug-fitting relationship with the inner surface of can112. A weld 114 hermetically secures the lid to the can. Also can 112 isshown having a curved bottom wall.

The anode electrode 12 and cathode electrode 14 are activated andoperatively associated with each other by an electrolyte solution filledin the casing through the electrolyte fill opening 38. Any electrolytethat is known to activate the particular anode and cathode activematerials selected to provide acceptable capacitive performance over adesired operating range is contemplated by the scope of the presentinvention. Suitable electrolytes include sulfuric acid in an aqueoussolution. Specifically, a 38% sulfuric acid solution has been shown toperform well at voltages of up to about 125 volts. A 10% to 20%phosphoric acid/water solution is known to provide an increasedequivalent series resistance (ESR) and breakdown voltage. Other suitableelectrolytes are contemplated that provide desired performancecharacteristics.

Referring to FIG. 2, lid 30 is provided with the closure structure 40for the electrolyte fill opening 38 preferably having a slightlyinwardly closing taper that receives a metal ball 116 secured therein byweld 118. Alternate embodiments of the closure structure are shown inFIGS. 10 and 11. In FIG. 10, a ring 120 having a cylindrical opening issecured to the under surface of lid 30 disposed coaxially with opening38. Metal ball 116 is wedged in the opening of ring 120 to prevent outgassed by-products as a closure plate 122 is disposed in the opening ina snug fitted relationship and secured therein by weld 124.

FIG. 10A shows a plug 121 having an enlarged head 123 and a curved end125 welded at 127. If desired, plug 121 does not require the enlargedhead 123 and/or the curved end 125 to provide a suitable closure for theelectrolyte fill opening 38.

FIG. 11 illustrates another embodiment of the seal structure wherein theportion of lid 30A immediately adjacent to the fill opening 38 isdeformed to have an annularly curved portion 126 that matches thecurvature of ball 116. Ball 116 is received in the curved portion 126and secured in place by weld 128 to complete the seal. For a moredetailed discussion of closure structures suitable for use with thepresent invention, reference is made to U.S. Pat. No. 5,776,632 toHonegger, entitled “Hermetic Seal For An Electrochemical Cell”, which isassigned to the assignee of the present invention and the disclosure ofwhich is incorporated herein by reference.

FIGS. 12 to 15 illustrate alternate embodiments of capacitors accordingto the present invention having generally flat, planar geometriesincluding side walls provided with electrode active material. Other thanthe various casing structures which are described immediately below, thecapacitors of FIGS. 12 to 15 are similar to the capacitor 10 shown inFIGS. 1 to 3. FIG. 12 shows a capacitor 130 having side walls 132 and134 which are welded to a ring 136 after being selectively provided withthe electrode active material 42 in a similar manner as previouslydescribed with respect to capacitor 10.

FIG. 13 shows another embodiment of a capacitor 140 according to thepresent invention fabricated from an electrode active material 42selectively contacted to a substrate provided in the shape of a cuphaving an annular side wall 142 extending from a bottom wall 144. Theside wall 142 forms into an annular rim 146 which is generally normal tothe plane of side wall 142. The rim 146 is connected to lid 148 by weld150 to complete the enclosure.

FIG. 14 shows another embodiment of a capacitor 152 according to thepresent invention fabricated from an electrode active material 42selectively contacted to a substrate provided in the shape of traymembers 154 and 156. An annular back-up ring 158 fits inside the sidewall portions of the trays 154, 156 to provide support when the traysare connected together along their respective edges by weld 160 tocomplete the casing enclosure.

FIG. 15 illustrates an alternate embodiment of a capacitor 170 accordingto the present invention fabricated from a first substrate provided withan electrode active material 42 selectively contacted thereto and formedto provide a side wall 172 disposed intermediate opposed bottom and lidwalls 174 and 176, respectively. A second substrate selectivelycontacted with an electrode active material 42 is formed to provide asecond side wall 178 disposed intermediate opposed bottom wall 180 andlid 182. Second side wall 178 is somewhat shorter in length than sidewall 172 so that bottom wall 180 and lid 182 are overlapped by bottomwall 174 and lid wall 176 secured therein by welds 184 and 186. Again,opposed end walls (not shown) complete the casing enclosure.

FIG. 16 shows an embodiment of side-by-side capacitor cells 188 and 190connected in parallel according to the present invention. The capacitorcells are housed in a deep drawn can 192 having the capacitive cathodeactive material 42 contacted to the opposed side walls 194 and 196. Anintermediate side wall 198 extends from a mid-point of the bottom wall200 and is provided with the cathode active material 42 on the opposedsides thereof. Anode active pellets 12A and 12B are disposed between theside wall 194 and intermediate wall 198 and between the intermediatewall and side wall 196, respectively. The anodes 12A and 12B areenveloped in respective separators 202 and 204. Terminal lead 34 extendsfrom anode 12B which in turn is connected in parallel to anode 12A vialead 206. The insulator and seal structure 78 shown in FIG. 6 isolatesthe terminal lead 34 from the lid 30B connected to can 192 by a weld208. An electrolyte (not shown) is filled in the casing to operativelyassociate and activate the capacitors. This side-by-side capacitor cellsconstruction provides for reduced ESR in comparison to the capacitorsshown in FIGS. 1 to 3 and 12 to 15, and further provides a constructionby which increased cathode active material may be housed inside of acasing. Of course, those skilled in the art will realize that thecapacitor embodiment shown in FIG. 16 need not be limited to twoside-by-side capacitor cells but that two or more cells as desired maybe connected in parallel according to the present invention.

The present capacitor constructions having the generally flat, planargeometry have been shown to improve the volumetric efficiency of acapacitor by about 15% to about 80% over that of standard cylindricallyshaped capacitors of a comparable casing size. Further, it has beendetermined that the capacitance obtained from an electrode made from anultrasonically generated aerosol of active material contacted to agenerally flat, planar geometry according to the present invention is onthe order of about 2 F/sq. in. as measured by AC impedance spectroscopy.

It is appreciated that various modifications to the inventive conceptsdescribed herein may be apparent to those skilled in the art withoutdeparting from the spirit and the scope of the present invention definedby the hereinafter appended claims.

What is claimed is:
 1. A method for providing a capacitor, comprisingthe steps of: a) providing a casing; b) providing a first electrodecomprising a capacitive material as a first electrode active materialcontacted to a conductive substrate in the form of an ultrasonicallygenerated aerosol of the first electrode active material, wherein atleast a portion of a side wall of the casing is provided by theconductive substrate itself or the conductive substrate is in electricalcontact with the side wall forming the casing for the capacitor; c)positioning a second electrode inside the casing connected to a secondelectrode terminal insulated from the casing by a glass-to-metal seal;d) filling an electrolyte into the casing; and e) hermetically sealingthe casing.
 2. The method of claim 1 including providing theultrasonically generated aerosol comprising aerosol particles, amajority of which have diameters of less than about 10 microns.
 3. Themethod of claim 1 including providing the first electrode activematerial having an internal surface area of about 10 m²/gram to about1,500 m²/gram.
 4. A method for providing a capacitor, comprising thesteps of: a) providing a casing comprised of spaced apart side wallsjoined by a surrounding intermediate wall; b) providing a firstelectrode comprising a first electrode active material contacted to atleast one conductive substrate in electrical contact with a firstelectrode terminal wherein at least one of the side walls is provided bythe conductive substrate itself or the conductive substrate contactedwith the first electrode active material is in electrical contact withat least one of the side walls forming the casing for the capacitor; c)positioning a second electrode inside the casing at a positionintermediate the spaced apart side walls, wherein the second electrodeis connected to a second electrode terminal insulated from the casing bya glass-to-metal seal; d) filling an electrolyte into the casing; and e)hermetically sealing the casing.
 5. The method of claim 4 includingselecting the first electrode active material from the group consistingof an anodized-etched foil, a sintered active material with or withoutoxide, a double layer capacitive material, a semiconductive material, apseudocapacitive material and a conductive polymeric material.
 6. Themethod of claim 5 including forming the first electrode from an aerosolof the pseudocapacitive material comprising a first pseudocapacitivemetal compound or precursor thereof contacted to the conductivesubstrate and heated to a temperature to solidify the firstpseudocapacitive metal compound or convert the precursor to thesolidified pseudocapacitive metal compound.
 7. The method of claim 5including selecting the pseudocapacitive material from the groupconsisting of an oxide, a nitride, a carbon nitride and a carbide, andmixtures thereof.
 8. The method of claim 5 including selecting a firstmetal of the pseudocapacitive material from the group consisting ofruthenium, molybdenum, tungsten, tantalum, cobalt, manganese, nickel,iridium, iron, titanium, zirconium, hafnium, rhodium, vanadium, osmium,palladium, platinum and niobium, and mixtures thereof.
 9. The method ofclaim 5 including providing the pseudocapacitive material comprised of asecond metal.
 10. The method of claim 9 including selecting the secondmetal from the group consisting of tantalum, titanium, nickel, iridium,platinum, palladium, gold, silver, cobalt, molybdenum, niobium,ruthenium, manganese, tungsten, iron, zirconium, hafnium, rhodium,vanadium, osmium, and mixtures thereof.
 11. The method of claim 5including providing the pseudocapacitive material comprised of rutheniumand tantalum.
 12. The method of claim 5 including providing thepseudocapacitive material having a thickness of about a hundredAngstroms to about 0.1 millimeters.
 13. The method of claim 4 includingselecting the conductive substrate from the group consisting oftantalum, titanium, nickel, molybdenum, niobium, cobalt, stainlesssteel, tungsten, platinum, palladium, gold, silver, copper, chromium,vanadium, aluminum, zirconium, hafnium, zinc and iron, and mixtures andalloys thereof.
 14. The method of claim 4 including providing theconductive substrate having a thickness of about 0.001 to 2 millimeters.15. The method of claim 4 including increasing a surface area of theconductive substrate intended to be contacted with the first electrodeactive material prior to being contacted.
 16. The method of claim 4including providing the conductive substrate characterized as having hadits surface increased in electrical conductivity prior to beingcontacted with the first electrode active material.
 17. The method ofclaim 4 including providing the surrounding intermediate wall comprisingopposed end walls, a top wall and a bottom wall joined to the spacedapart side walls.
 18. The method of claim 4 including providing thecapacitor of an electrochemical type.
 19. The method of claim 4including providing the first electrode as the cathode and furtherincluding providing the second electrode as the anode comprising asecond electrode active material selected from the group consisting of asecond anodized-etched foil, a second sintered active material with orwithout oxide, a second double capacitive material, a secondpseudocapacitive material and a second conductive polymeric material.20. The method of claim 19 wherein the second pseudocapacitive materialis formed from an ultrasonically generated aerosol of the secondpseudocapacitive material.
 21. The method of claim 4 including providingthe capacitor of an electrolytic type.
 22. The method of claim 21including providing the anode in the form of a pellet.
 23. The method ofclaim 22 including sintering the pellet.
 24. The method of claim 23including providing an oxide layer on the sintered pellet.
 25. Themethod of claim 21 including selecting the anode from the groupconsisting of tantalum, aluminum, titanium, niobium, zirconium, hafnium,tungsten, molybdenum, vanadium, silicon, and germanium, and mixtures andalloys thereof.
 26. The method of claim 4 including providing the casingas the first electrode terminal.
 27. The method of claim 4 including aferrule member provided with at least one synthetic polymeric materialsealing between the second electrode terminal and an inner surface ofthe ferrule and further including a glass layer disposed between thesecond electrode terminal and the ferrule.
 28. The method of claim 4including providing a ferrule member sealed in a polymeric cup-shapedmember by a surrounding compression member secured to the casing. 29.The method of claim 4 including providing a metal sleeve sealed insideof a ferrule member by an insulative material and wherein the terminallead is received inside the sleeve and sealed thereto by a weld.
 30. Amethod for providing a capacitor, comprising the steps of: a) providinga casing comprised of spaced apart side walls joined by a surroundingintermediate wall; b) providing a first electrode comprising an activematerial of ruthenium and tantalum contacted to at least one conductivesubstrate in electrical contact with a first electrode terminal whereinat least one of the side walls is provided by the conductive substrateitself or active material is in electrical contact with at least one ofthe side walls forming the casing for the capacitor; c) positioning asecond electrode inside the casing at a position intermediate the spacedapart side walls, wherein the second electrode is connected to a secondelectrode terminal insulated from the casing by a glass-to-metal seal;d) filling an electrolyte into the casing; and e) hermetically sealingthe casing.
 31. The method of claim 30 including a ferrule memberprovided with at least one synthetic polymeric material sealing betweenthe second electrode terminal and an inner surface of the ferrule andfurther including a glass layer disposed between the second electrodeterminal and the ferrule.
 32. A method for providing a capacitor,comprising the steps of: a) providing a casing comprised of spaced apartfirst and second casing side walls joined by a surrounding casing endwall; b) providing a cathode electrode comprising a cathode activematerial in the form of an ultrasonically generated aerosol of thecathode active material contacted to at least two conductive substratesin electrical contact with a cathode terminal, wherein at least aportion of the first and second casing side walls are provided by theconductive substrates or the conductive substrates contacted with thecathode active material are in electrical contact with at least aportion of the first and second casing side walls; c) positioning aunitary anode electrode inside the casing intermediate the first andsecond casing side walls, wherein the anode electrode is connected to ananode terminal and having opposed first and second major faces joined byan intermediate anode end wall such that the first and second majorfaces are directly opposed by the respective spaced apart first andsecond casing side walls provided by the conductive substrates contactedwith the cathode active material or the conductive substrates contactedwith the cathode active material in electrical contact with at least aportion of the first and second casing side walls and with at least aportion of the intermediate anode end wall directly opposed by thecasing end wall, wherein the anode is an anodized-etched foil orsintered active material with or without oxide of one of the groupconsisting of tantalum, aluminum, titanium, niobium, zirconium, hafnium,tungsten, molybdenum, vanadium, silicon, germanium, and mixtures andalloys thereof; d) filling an electrolyte into the casing; and e)hermetically sealing the casing, wherein the capacitor is capable ofdelivering about 2 F/in.².
 33. The method of claim 32 wherein thecathode active material is a ruthenium-containing oxide and the anode isof sintered tantalum.